How-To: Change The Color Of Your 99-02 GMT800 HVAC Control Backlights.

[ScottyBoy]

Ok, most of you have already seen mods on how to change the instrument cluster lights to LED's. Now heres how to do basically the same thing to your AC control panel.

First off, remove the AC control panel from the truck. Now carefully pop odd the 3 control knobs. Now open up the switch by removing the 4 1/4 inch hex screws on the back.

 

Now carefully release the tabs holding the circuit board in the white part of the contol panel, work your way around untill it comes loose.

 

You can also unscrew the bottom board from the front panel by unscrewing the two 1/4inch hex scews.

The 4 stock bulbs on the bigger circuit board are wired in two pairs. Each pair is wired in series. So you will need to unsolder all 4 bulbs and on the two that I have circled, put a 330ohm resistor on the positive lead.

Here is how you want to orient the resistor into place. So it will line up the the two pinholes in the circuit board just like the stock bulb.

 

Stock bulb on the left, LED and resitor on the right.

 

After you solder in your LED's with resistors, follow the tracer on the circuit board to the bulb next to it. That pin is where you will solder in your positive lead for the next LED, ground in the other pinhole. Here is a shot with the two right ones done.

 

Now all four done.

 

Now you can move on to the smaller lower panel which lights up the buttons.

I've seen other sites say to do these with 3mm LED's (as the stock bulbs are about 3mm) but I put 5mm LED's and they fit just fine.

For the lower panel, you will need to solder in a 330 ohm resistor inline in the second wire from the right. This wire feeds the positive to all four of these bulbs.

 

Now simply unsolder the stock bulbs, and solder the LED's in their place. The thin tracer wire on each bulb is the positive lead. On these, I had to do a little trial and error getting the LED's tilted on a slight angle to fire at the button for the best possible light output to each switch. Heres the LED's in place.

 

Now all are done.

 

Now you can put the switch back together and go check it out in your truck. Here is a pic testing it on my power supply.

 

 

Here are a few pics of mine installed. The pics are crappy, I couldn't get the glare off the camera for shit! These pics do it no justice.

[sl33py24]

can u post one up for the instrument cluster lights to LED's.

[ScottyBoy]

can u post one up for the instrument cluster lights to LED's.

 

 

"Thunderstruck" already did a write up on how to do the cluster.

[jerseymike68]

Nice information

[tbagg69]

What resistors did you use the 1/4 , 1/8, or the 1/2 watt 330 ohm resistors

[ScottyBoy]

What resistors did you use the 1/4 , 1/8, or the 1/2 watt 330 ohm resistors

 

I used the 1/4 watt, but 1/2 watt will also work.

[crunch1191]

I already have 470 ohm resistors do I need order 330 ohm?

[Jerry m k]

I now have destroyed 2 temp control boards. Do you know who I can get to do my led change out on all my switches. I've done the cluster.

[Daryl Z71]

I now have destroyed 2 temp control boards. Do you know who I can get to do my led change out on all my switches. I've done the cluster.

There are a few different sellers on Ebay that offer this service.

[ScottyBoy]

There are a few different sellers on Ebay that offer this service.

I do actually offer this service as well. There have been quite a few members on several different truck forums that have sent me their switches and panels to have me install blue LEDs in them because they either didn't have good soldering skills or else they were just too hesitant to tackle the project themselves.

I charge $50 to do an AC control panel. Most other switches are in the $20 to $35 range depending on which switch it is. Parts and labor is included, but shipping is extra. Just send me a PM and we can discuss.